What is the differenc e between drift diffusion current?

Specifically, drift relates the movement of a carrier (e.g., an electron or hole) to an applied electric field (i.e., the velocity of the carrier is proportional to the electric field, where the proportionality constant, mobility, is a quantity derived in solid-state physics). Diffusion relates the movement of carriers due to random (i.e., thermal) behavior and non-uniform distribution (i.e., the velocity of the carrier is proportional to the logarithmic derivative of the density of carriers, where the proportionality constant, the diffusion constant, is a quantity derived in solid-state physics).